Variable Schedule Protocol Summaries

Fixed Ratio (FR):

• A response is reinforced only after a specified number of responses
• Produces a high, steady rate of responding with only a brief pause after the delivery of the reinforcer

Fixed Interval (FI):

• The first response is rewarded only after a specified amount of time has elapsed
• Causes high amounts of responding near the end of the interval, but much slower responding immediately after the delivery of the reinforcer

Variable Ratio (VR): 

• Gambling and lottery games are good examples of a reward based on a variable ratio schedule
• Creates a high steady rate of responding
• A response is reinforced after an unpredictable number of responses
• Mean of 5 with a range from 1 to 10 responses

Variable Interval (VI): 

• A response is rewarded after an unpredictable amount of time has passed
• Produces a slow, steady rate of response
• Mean of 7 seconds and a range from 3 to 10 seconds